This isn't a bee, but actually a Robber Fly. The Asilids of the genus Mallophora strongly resemble bees in the genus Bombus. They actually prey on them as well. This is a mating pair, though the second one is out of focus

This is the best find from my Lake Tahoe trip. Dr. Eric Fisher ID'd this as Pogonosoma ridignsi and said that it's not very common. It's in the subfamily Laphriinae. This is also one of the cuter robbers I shot.